I think I'm starting to get it, and I think Tony and Al are right. Horsepower is a measure of work an engine can do in a certain time, (torque*revolutions per minute)/5252, torque is a direct measure of the force being put through the drivetrain to accelerate the car at any given rpm point. The point with the most force is the point of most acceleration, most force pushing through the drivetrain to push the car forward. Continuing past that point is just letting gear multiplication increase the torque put to the ground over time (work, hp) because there will still be more torque with the multiplication than there would be even at peak in the next gear. This is how you use gearing to harness hp (torque at high rpm) to do work, but max accelerative force to the ground in any given gear will be the torque peak. Go to the next gear and your multiplication is much less.

HP has always just been a very rough way to estimate the powerband of an engine. If you have a hp peak at a high rpm and a low torque peak figure high rpm, it's a high-winding peaky engine. If you have lower hp at a low rpm and high torque at a low rpm, it's an engine with low-end grunt that doesn't do well at high rpm.